So what happens when things rub together (e.g. your hands)? We observe friction. Heat energy is released (kinetic energy transformed into heat energy). If we rub our hands together for a week without stopping, what would happen to our skin (peel off, wear off)? Same happens to steel surfaces in a car engine. What would we use to prevent it (engine oil)? Other lubricants: grease, sometimes also water or air and other substances.
space shuttle Columbia 2003 destroyed on reentry. thermal protection system failed – high heat in the upper atmosphere due to frictional heating up caused an explosion. Q&A: why does it heat up? what is air made of? elicit: air particles rub against the surface of the space shuttle. As it goes at a very high speed, this releases a lot of energy in form of heat. Can that happen in outer space / vacuum / outside the atmosphere? no, because there are no particles
Low friction can be useful as well, but can be dangerous in some situations.
maximizing and minimizing friction by equipment design and sport techniques.
Lubricant extracted from the piston assembly of a gasoline engine has been chemically analysed to determine the level of degradation and the level and type of volatile carbon containing species. Using FIMS, the oil samples contain a noticeable amounts of volatile hydrocarbons, with molecular masses ranging from the fuel-sized to lubricant-sized molecules, and GC-MS reveals that they are alkyl benzenes and alkyl polyaromatic hydrocarbons; species of interest because they are both reactive and toxic. The effect of these species on the viscosity of the lubricant and the mechanism of their formation are discussed.
One factor that controls the oil drain intervals of automotive engines is how fast it flows through the piston assembly, where it is subjected to high temperatures and corrosive blow-by gases, and returns degraded to the sump. Building on previous work, this flow rate has been measured, and its dependence on engine load and speed established.
A big effort is addressed to researches on surface topography, contact mechanics aspects, and particularly on surface coatings and treatments. Indentation and scratching techniques are used for the characterization of both coatings and bulk materials down to the nanoscale. Mechanical characterization of materials and mat- erial processing involve tribological aspects too. Investigations on the wear behaviour of different materials for applications in the field of biotribology are also being carried out. The increasing interest of the industrial world in tribological problems is producing a lot of collaborations among universities, research centres, and industries. Several tribological components and practical applications are investigated, such as lubricated sliding bearings, gas and magnetic bearings, gears, sealing systems, and automotive and rail components. Investigations are often completed by diagnostic studies for monitoring or maintenance purposes. A flexure journal bearing design is proposed that will improve operational behaviour of a journal bearing at pronounced misalignment. Using a thermoelastohydrodynamic model,
Ppt on tribology.pp
Tanvir L. Shaikh
B. E. Mechanical
TRENDS IN TRIBOLOGYTRENDS IN TRIBOLOGY
WHERE IS TRIBOLOGY?
Mechanisms: Gears, bearings, rail wheels
What is wear?
It’s the removal of
material from a solid
surface by the action of
Why do we need it?
remove heat and
lower the friction
LUBRICATION OF ENGINE
Lubricant extracted from the piston assembly of a gasoline engine has been
chemically analysed to determine the level of degradation and type of
volatile carbon containing species.
Improvement of journal bearing operation at
heavy misalignment using bearing flexibility and
Tribological surface coatings
Lubrication and Life of Polymer Rolling Bearings
Bearing film thickness analysis
In U. S., there is Argonne's Tribology Laboratory
to conduct research on advanced tribological
systems (surface engineered materials,
lubricants, fuels and additives).
The Lab's "toolbox" includes :
RECENT RESEARCH IN U. S.
To study wear in engines and
drivelines, the amount of material
loss is measured using the optical
MicroXAM surface profiler
This machine can do a wide variety of severe-contact
tribological tests that assess the friction and wear-
prevention properties of lubricants.